Automatic valve

Abstract

A compact automatic valve has a cylindrical body with a sleeve inserted to move in the cylindrical body in the axial direction. A first diaphragm, having an annular joint section and an annular protrusion arranged in the outer circumferential section, is joined to one end of the sleeve. A second diaphragm, having an annular joint section and an annular protrusion arranged in the outer circumferential section, is joined to the other end of the sleeve. A first cylindrical diaphragm presser, joined to one end of the cylindrical body, presses the annular protrusion of the first diaphragm and a second cylindrical diaphragm presser, joined to the other end of the cylindrical body, presses the annular protrusion of the second diaphragm. Both the first cylindrical diaphragm presser and the second cylindrical diaphragm presser have a fluid communicating port. A valve member, which is contacted with and separated from the lower end of the sleeve, is arranged at the center of the bottom of the second cylindrical diaphragm presser and alternatively contacts with or separates from the lower end of the sleeve as the sleeve moves axially to close or open the valve. A pair of fluid supply ports respectively communicate with an upper and a lower clearance formed by the cylindrical body, diaphragms and sleeve.

What is claimed is:  
     
       1. An automatic valve comprising: 
       a cylindrical body;  
       a sleeve inserted into the cylindrical body so that the sleeve can be moved in the cylindrical body in an axial direction;  
       a first diaphragm having an annular joint section joined to a first end of the sleeve and also having an annular protrusion arranged in an outer circumferential section of the first diaphragm;  
       a second diaphragm having an annular joint section joined to a second end of the sleeve and also having an annular protrusion arranged in an outer circumferential section of the second diaphragm;  
       a first cylindrical diaphragm presser for pressing the annular protrusion of one of the first and second diaphragms, the first cylindrical diaphragm presser being joined to a first end of the cylindrical body, the first cylindrical diaphragm presser having a fluid communicating port;  
       a second cylindrical diaphragm presser for pressing the annular protrusion of the other of the first and second diaphragms, the second cylindrical diaphragm presser being joined to a second end of the cylindrical body;  
       a valve member, which is alternatively contacted with and separated from the second end of the sleeve, being arranged at the center of the bottom of the second cylindrical diaphragm presser, the second cylindrical diaphragm presser having a fluid communicating port;  
       and a pair of fluid supply ports, one of the fluid supply ports communicating with an upper clearance formed by the cylindrical body, one of the first and second diaphragms and the sleeve, the other fluid supply port communicating with a lower clearance formed by the cylindrical body, the other of the first and second diaphragms and the sleeve.  
     
     
       2. An automatic valve according to claim  1 , wherein one of the first and the second diaphragm is integrated with the sleeve. 
     
     
       3. An automatic valve according to claim  1 , wherein both the first and second diaphragms are integrated with the sleeve. 
     
     
       4. An automatic valve according to claim  1 , wherein the fluid communicating port of the first diaphragm presser and the fluid communicating port of the second diaphragm presser are formed on the sides of the respective diaphragm presser. 
     
     
       5. An automatic valve according to claim  1 , wherein the cylindrical body is a one-piece body having a unitary construction. 
     
     
       6. An automatic valve according to claim  5 , wherein the first cylindrical diaphragm presser and the second cylindrical diaphragm presser threadably engage the one-piece body. 
     
     
       7. An automatic valve according to claim  5 , wherein both of the fluid supply ports are formed in the one-piece body.